I can't figure this one out...a user in a remote office was having problems with his Blackberry (not sure of model, it's not a 7100) where the screen would go dark or it would turn off while he was using it. It seemed to have a good battery strength. A new battery didn't help, and a new Blackberry does the same thing. When he got the replacement, he plugged it in, switched the pin assigned to him in BES and was moving the mouse to create a new key. The screen went dark and the led started flashing. This new unit did not have any of his data on it yet. Is it possible for the sim card to cause this? That seems to be the only thing left.